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Subject[PATCH] x86: Unspaghettize do_trap()
Date
Cleanup the label maze in this function. Having a
seperate function to first handle the traps that don't
generate a signal makes it easier to convert into
more readable conditional paths.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
---
arch/x86/kernel/traps.c | 58 ++++++++++++++++++++++------------------------
1 files changed, 28 insertions(+), 30 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b481341..1a8dd87 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -107,30 +107,45 @@ static inline void preempt_conditional_cli(struct pt_regs *regs)
dec_preempt_count();
}

-static void __kprobes
-do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
- long error_code, siginfo_t *info)
+static int __kprobes
+do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str,
+ struct pt_regs *regs, long error_code)
{
- struct task_struct *tsk = current;
-
#ifdef CONFIG_X86_32
if (regs->flags & X86_VM_MASK) {
/*
* traps 0, 1, 3, 4, and 5 should be forwarded to vm86.
* On nmi (interrupt 2), do_trap should not be called.
*/
- if (trapnr < X86_TRAP_UD)
- goto vm86_trap;
- goto trap_signal;
+ if (trapnr < X86_TRAP_UD) {
+ if (!handle_vm86_trap((struct kernel_vm86_regs *) regs,
+ error_code, trapnr))
+ return 0;
+ }
+ return -1
}
#endif
+ if (!user_mode(regs)) {
+ if (!fixup_exception(regs)) {
+ tsk->thread.error_code = error_code;
+ tsk->thread.trap_nr = trapnr;
+ die(str, regs, error_code);
+ }
+ return 0;
+ }

- if (!user_mode(regs))
- goto kernel_trap;
+ return -1;
+}

-#ifdef CONFIG_X86_32
-trap_signal:
-#endif
+static void __kprobes
+do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
+ long error_code, siginfo_t *info)
+{
+ struct task_struct *tsk = current;
+
+
+ if (!do_trap_no_signal(tsk, trapnr, str, regs, error_code))
+ return;
/*
* We want error_code and trap_nr set for userspace faults and
* kernelspace faults which result in die(), but not
@@ -158,23 +173,6 @@ trap_signal:
force_sig_info(signr, info, tsk);
else
force_sig(signr, tsk);
- return;
-
-kernel_trap:
- if (!fixup_exception(regs)) {
- tsk->thread.error_code = error_code;
- tsk->thread.trap_nr = trapnr;
- die(str, regs, error_code);
- }
- return;
-
-#ifdef CONFIG_X86_32
-vm86_trap:
- if (handle_vm86_trap((struct kernel_vm86_regs *) regs,
- error_code, trapnr))
- goto trap_signal;
- return;
-#endif
}

#define DO_ERROR(trapnr, signr, str, name) \
--
1.7.5.4


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